Electrical Question

[Lead Head]

Are there any very fast acting circuit breakers? I just bout a 20 amp circuit breaker for use with my transformer, so I shorted the leads off my transformer out, but it blew my 25 amp rectifier, and the breaker didn't trip. Am I missing something here? Or are fuses my only option?

[Reloadron]

Originally Posted by Lead Head

Are there any very fast acting circuit breakers? I just bout a 20 amp circuit breaker for use with my transformer, so I shorted the leads off my transformer out, but it blew my 25 amp rectifier, and the breaker didn't trip. Am I missing something here? Or are fuses my only option?

Fuses are your best option. A typical 20 Amp household circuit breaker will only instantly trip at 100 Amps (5X the rated load). I tend to recall 5X from a recent course I had to take for safety. Less than 5X the time increases before break. I would place a 20 Amp Fast Acting fuse on the hot side of the AC line input.

I am guessing you have a 25 Amp full wave bridge rectifier rated at what voltage?

I know I have a full breakdown of circuit breaker trip times somewhere just not where I thought, maybe laying in the truck. A Google may get you more on target. Think it is covered in the NEC (National Electric Code) and another safety related publication I can't remember. Been a long day and I am tired.

Ron

[Lead Head]

Its a 25 amp full wave 50 v rectifier. I got some 10 guage wire from my dad's work, so I re-wried the MOT with it. No load, it puts out around 11.5 vAC, or around 12.1 vDC rectified, but that drops to around 9-10 volts under load (linear FTL).

But this thing can move some serious current, I was testing it earlier, and stuck the handle from a binder clip onto the output (this is after the rectifier fried), and as soon as I plugged it in, there was a quick loud buzzing, a spark, and a half second later I see the paper clip 2 feet away and very hot

I'm guessing at the time I fried the rectifier I was at least pushing 30-40 amps through the rectifier, since its puked brown smoke after about .8 seconds of being shorted.

Would it be better to put the fuse on the DC side, as to protect the rectifier, vs. putting on the AC side? Should I keep the circuit breaker in there as insurance or at least a main disconnect. I'd hate to see it go to waste since I just paid $4 for it

Just did another experiment, hooked the breaker directly upto the transformer output, as soon as I plugged it in, the breaker instantly tripped. So I atleast know this transformer can provide upto 100 amps, at least for a few seconds :-P

[Reloadron]

Originally Posted by Lead Head

Its a 25 amp full wave 50 v rectifier. I got some 10 guage wire from my dad's work, so I re-wried the MOT with it. No load, it puts out around 11.5 vAC, or around 12.1 vDC rectified, but that drops to around 9-10 volts under load (linear FTL).

But this thing can move some serious current, I was testing it earlier, and stuck the handle from a binder clip onto the output (this is after the rectifier fried), and as soon as I plugged it in, there was a quick loud buzzing, a spark, and a half second later I see the paper clip 2 feet away and very hot

I'm guessing at the time I fried the rectifier I was at least pushing 30-40 amps through the rectifier, since its puked brown smoke after about .8 seconds of being shorted.

Would it be better to put the fuse on the DC side, as to protect the rectifier, vs. putting on the AC side? Should I keep the circuit breaker in there as insurance or at least a main disconnect. I'd hate to see it go to waste since I just paid $4 for it

Just did another experiment, hooked the breaker directly upto the transformer output, as soon as I plugged it in, the breaker instantly tripped. So I atleast know this transformer can provide upto 100 amps, at least for a few seconds :-P

OK, I was wondering how you made out on the rewind using heavier gage wire.

Yeah, you can fuse the secondary side. I would fuse after the rectifier.

Keep something in mind. The transformer you started with I believe was from a microwave oven without looking back. Pretty beefy as you noticed. It was also used as a "step up" to generate the high voltage for the magnetron in the microwave oven. You are now using it as a step down having rewound the secondary.

Just winging it, you can figure the primary winding is pretty beefy and now you added a pretty beefy secondary winding. Think a transformer used in Welding Apps. Low voltage secondary but tremendous current.

Looking at things unloaded if you measure your input voltage (about 120 VAC) and your output voltage you can get an idea of the turns ratio.

Anyway, yes fusing the recrifier would be a good idea using a fast acting fuse. Additionally heat sink it if you havent already.

Ron

[Lead Head]

The rectifier is stuck to the side of the transformer, and I'm using that as its heatsink. I actually have to actively cool the transformer though, even under light load. I stuck a copper and alu heatsink on the top and bottom, and I have fans on them, to keep the transformer cool. I did some research on it, and I guess to keep costs down, the manufactures put as few turns as possible in the primary coil, to keep costs down, but you get extra heat in return.

[Reloadron]

I did mess with using Hydrogen Electrolysis to produce hydrogen and oxygen, many, many years ago. The problem then as it is now was that you could make hydrogen real easy, however, the cost of using electrolysis was it cost more to make than it was worth. You would spend more energy making it that you could get in return. However it was fun to mess with.

Years ago basic 1.5 Volt D cell batteries were a carbon (or graphite) rod (+) surrounded by a Zinc paste in a Zink can. We would split batteries open to get the carbon or graphite rods and use them as our electrodes. I sort of remember the pictures you posted and was wondering what you were using for electrodes? We would also add some salt to the water to increase the conductivity.

I don't remember needing massive current, I think I used an old Tyco HO gage train transformer for my DC supply. Took awhile but you got hydrogen and oxygen.

Yeah, today's transformers for home appliances are not what they once were. Think cheap, is a manufacturing standard. Wait as the final impact of the cost of copper settles in.

Needless to say, be careful. Don't toast anything and above all else don't toast yourself.

Ron

[Lead Head]

Right now I have some aluminum heatsinks, but I just acquired some 3/16 stainless steel

[Reloadron]

Originally Posted by Lead Head

Right now I have some aluminum heatsinks, but I just acquired some 3/16 stainless steel

No, I mean in the water you have electrodes right?

As to the heat sinks, aluminum may be the best choice as aluminum is a better conductor of heat that SS in heat sinks.

Ron

[Lead Head]

I meant, the aluminum heatsinks are my electrodes. I just got some stainless to replace them.

I'm using OTHER aluminum/copper heatsinks to cool the transformer

[Reloadron]

Originally Posted by Lead Head

I meant, the aluminum heatsinks are my electrodes. I just got some stainless to replace them.

I'm using OTHER aluminum/copper heatsinks to cool the transformer

OK, got it. Would be cool if you could find some carbon or graphite rod stock. That would make sweet electrodes.

Ron